Influence of Silicon Source on the Steel Cleanness

Silicon is commonly used as a deoxidizer in the steel industry. The addition of silicon in the steel melt during refining is carried out in the form of ferrosilicon and commercial pure silicon. Ferrosilicon is widely used due to economic reasons. The non-metallic particles form when silicon is added into the steel melts, termed non-metallic inclusions. The impurities of the silicon source could lead to a change in the composition of the inclusion. In the present study, high-temperature experiments were carried out in the liquid steel at 1873 K at a laboratory scale. The effect of both silicon sources, i.e., high-purity silicon and ferrosilicon, on the steel cleanness were comparatively analysed. Pure silica inclusions were observed in the solidified steel samples at all silicon concentrations when high-purity silicon was added. However, apart from the silica, Si-Al-Ti-O complex inclusions were also observed in the case of the ferrosilicon addition, owing to its impurities. Thermodynamic analysis was carried out to support the experimental results.